The present invention relates to an adapter for use in compressing the valve springs of an internal combustion engine. More specifically, the present invention relates to an adapter which makes it possible to compress the valve springs of an overhead cam engine using a C-clamp.
On older engines, the valve springs typically extend upward from the upper surface of the engine cylinder head. Therefore, the valve springs may be compressed for the purpose of removing the valve assembly or for other purposes using a conventional C-clamp compressor of the type described, for example, in U.S. Pat. 1,862,793 and 1,913,084, incorporated herein by reference.
More recently, in overhead cam engines, the valve springs are frequently surrounded by a structure which precludes the use of the conventional C-clamp compressor. As a result, tools like that shown in U.S. Pat. No. 4,176,435 have appeared, in which a crossbar is first mounted on the cylinder head permitting use of a leverage arm or pry bar with a metal sleeve on the leverage arm engaging the valve spring assembly and compressing it as a force is applied to the leverage arm. The arrangement shown in U.S. Patent 4,176,435 is for the purpose of removing a rocker arm, but a similar arrangement is also known with openings at each side of the sleeve to permit removal of the collets which hold the valve spring retainer and the valve spring in place. This arrangement, however, requires a special crossbar or similar jig for each type of cylinder head, so that if several types of engines are being repaired, it will be necessary to have several types of crossbars on hand. Furthermore, since the spacing of the sleeve from the end of the lever arm is fixed, it may be necessary to have more than one lever arm as well.
It would be advantageous to have a technique for compressing the valve spring of an overhead cam engine which would not require a special crossbar or tool for each engine, but which could be used with many different types of cylinder heads. It would also be advantageous to provide a technique which would not risk scoring or scratching the cam tappet bore in the cylinder head by a metal sleeve.